JP2012233021A - Method for manufacturing polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyimide film, which does not cause appearance defects and a decrease in strength, and whitening and the like involved in the imidization reaction.SOLUTION: The method for manufacturing a polyimide film includes: (a) a step of coating on a support a polyamic acid-containing solution obtained by reacting a specific tetracarboxylic dianhydride with a specific diamine in a solvent; (b) a step of drying the solvent in the polyamic acid-containing solution at a temperature of 150°C or lower until a polyamic acid-containing film composed of a coating film of the polyamic acid-containing solution becomes tack-free; (c) a step of peeling the polyamic acid-containing film from the support; and (d) a step of fixing and heating the polyamic acid-containing film while the temperature is being raised from 150°C or lower to imidize the polyamic acid to thereby obtain the polyimide film.

Description

  The present invention relates to a method for producing a polyimide film.

  Polyimide generally has superior heat resistance, mechanical properties, and electrical properties compared to other general-purpose resins and engineering plastics. Therefore, they are widely used in various applications as molding materials, composite materials, electric / electronic materials, optical materials, and the like. Particularly, a polyimide metal laminate having a metal foil and a polyimide layer used as a flexible printed board or the like needs to have reduced warpage. However, in general, polyimide has a larger coefficient of thermal expansion (CTE) than metal, which may cause warpage of the polyimide metal laminate.

  Further, in the display field such as a liquid crystal display element and an organic EL display element, inorganic glass, which is a transparent material, is widely used as a panel substrate. Inorganic glass has problems such as high specific gravity (weight), brittleness, and low flexibility. Therefore, studies are underway on transparent materials to replace glass. A plastic film made of a heat-resistant transparent resin has advantages such as light weight, impact resistance, and excellent workability. Furthermore, the use of the plastic film is expected to develop a flexible display which is very difficult with inorganic glass.

  As a material for a plastic film made of a heat-resistant transparent resin, for example, a polyimide containing cyclohexanediamine (CHDA) as a diamine component has been reported (see Patent Documents 1, 2, 3, and 4). Polyimide having cyclohexanediamine as a diamine component may have a characteristic that the coefficient of thermal expansion (CTE) is small (see, for example, Example 3 of Patent Document 1). Moreover, since it is an alicyclic structure, the colorless transparency of this polyimide is remarkably excellent compared with a wholly aromatic.

  However, since a polyimide having such a structure is usually insoluble in a solvent, a solution casting method which is a general film molding method cannot be used. Therefore, when a polyimide film is obtained, a polyamic acid-containing solution obtained by reacting an acid anhydride and a diamine is usually applied on a support, and the solvent is removed. obtain. Furthermore, a polyimide film is obtained by subjecting this polyamic acid film to heat treatment or chemical treatment.

  For example, in Patent Document 5, after a polyamic acid is applied to a glass substrate and dried at 70 ° C. for 1 hour to form a polyimide precursor film, thermal imidization is performed at 350 ° C. for 1 hour to obtain a 15 μm thick film. A polyimide film is obtained. However, the film obtained by the method described in Patent Document 5 is easily curled. Moreover, since it is difficult to peel off the glass substrate and the polyimide film, it is difficult to produce a polyimide film with a roll-to-roll, and there is a problem in productivity.

  Then, the manufacturing method of the polyimide film which apply | coats polyamic acid on a support body to make a polyamic acid containing film, peels this polyamic acid containing film from a support body, and is heated at 200 degreeC or more and imidated is disclosed. (Patent Document 6).

JP 2007-169304 A JP 2008-81718 A JP 2007-231224 A JP-A-9-176315 Patent No. 3972600 JP 2009-275090 A

  However, with the method of Patent Document 6, a polyimide film without curling is obtained, but poor appearance (foaming or the like) tends to occur in the obtained polyimide film. In addition, problems such as a decrease in strength, whitening accompanying an imidization reaction, and an increase in linear expansion coefficient are likely to occur.

  This invention is made | formed in view of such a situation, and provides the method of manufacturing a polyimide film, without producing the appearance defect (foaming etc.), intensity | strength reduction, and also the whitening etc. accompanying an imidation reaction. With the goal.

  As described above, in order to suppress curling of the polyimide film, it is important to imidize the polyamic acid with the polyamic acid-containing film peeled from the support. The inventors of the present invention have found that, when the polyamic acid is imidized, by heating the polyamic acid-containing film from a low temperature, the resulting polyimide film does not cause poor appearance or whitening, and the present invention has been achieved. .

（一般式（Ａ）中、Ｒは炭素数４〜２７の４価の基を示し、かつ
脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す。）

The present invention relates to the following method for producing a polyimide film.
[1] a) At least one selected from the group consisting of tetracarboxylic dianhydrides represented by the following general formula (A) and diamines represented by the following general formulas (B-1) to (B-3). A step of coating a polyamic acid-containing solution containing a polyamic acid on a support obtained by reacting a diamine containing a seed in a solvent; and b) a polyamic acid-containing film comprising a coating film of the polyamic acid-containing solution. A step of drying the solvent in the polyamic acid-containing solution at a temperature of 150 ° C. or lower until tack-free, c) a step of peeling the polyamic acid-containing film from the support, and d) the polyamic acid-containing film. Fixing the polyamic acid-containing film while raising the temperature from 150 ° C. or less, and imidizing the polyamic acid to obtain a polyimide film. Method for producing an imide film.

(In the general formula (A), R represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, a monocyclic aromatic group, Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group directly or by a bridging member Non-condensed polycyclic aromatic groups linked to each other are shown.)

[2] The method for producing a polyimide film according to [1], further including a step of e) heating the polyimide film at 200 ° C. or higher after the step d).
[3] At the same time as step e) or after step e), f) fixing the periphery of the polyimide film while heating at 200 ° C. or higher, and stretching the polyimide film by 0% to 300%. The manufacturing method of the polyimide film as described in [2].
[4] The polyimide film according to any one of [1] to [3], wherein step d) is a step of heating the polyamic acid-containing film while raising the temperature from 150 ° C. or lower to 200 ° C. or higher. Production method.
[5] The method for producing a polyimide film according to [4], wherein an average rate of temperature increase in the temperature range of 150 ° C. to 200 ° C. in step d) is 0.25 to 50 ° C./min.

[6] The method for producing a polyimide film according to any one of [1] to [5], wherein the step b) is a step in which the concentration of the solvent remaining in the polyamic acid-containing film is 1 to 50% by weight.

（一般式（Ｃ）及び（Ｄ）中、Ｒ及びＲ”はそれぞれ独立して、炭素数４〜２７の４価の基を示し、かつ脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す。一般式（Ｄ）において、Ｒ’は、炭素数４〜５１の２価の基であり；かつ脂肪族基、単環式脂肪族基（但し、１，４−シクロヘキシレン基を除く）、縮合多環式脂肪族基、単環式芳香族基もしくは縮合多環式芳香族基であるか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基であるか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基である） [7] The polyamic acid-containing solution includes a polyamic acid block composed of a repeating structural unit represented by the following general formula (C) and a polyimide composed of a repeating structural unit represented by the following general formula (D) The manufacturing method of the polyimide film in any one of [1]-[6] containing the block polyamic-acid imide containing a block.

(In the general formulas (C) and (D), R and R ″ each independently represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, or a condensed polycycle. Represents a non-condensed polycyclic aliphatic group in which a cyclic aliphatic group, a monocyclic aromatic group, or a condensed polycyclic aromatic group, or a cyclic aliphatic group connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a bridging member, wherein R ′ is a divalent group having 4 to 51 carbon atoms; Yes; and an aliphatic group, a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group), a condensed polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group Or a cyclic aliphatic group is directly or non-condensed polycyclic aliphatic group linked together by a bridging member, or an aromatic group is directly Or non-condensed polycyclic aromatic groups linked to each other by a bridging member)

（一般式（Ｅ）中、Ｒは炭素数４〜２７の４価の基を示し、かつ
脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す。） [8] The polyamic acid has a repeating unit represented by the following general formula (E), and the 1,4-bismethylenecyclohexane skeleton (X) in the general formula (E) is represented by the formula (X1). It is composed of a trans isomer and a cis isomer represented by the formula (X2), and the content ratio of the trans isomer to the cis isomer (trans isomer + cis isomer = 100%) is 60% ≦ trans isomer ≦ 100%, 0% The manufacturing method of the polyimide film as described in any one of [1]-[6] which is <= cis body <= 40%.

(In General Formula (E), R represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, a monocyclic aromatic group, Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group directly or by a bridging member Non-condensed polycyclic aromatic groups linked to each other are shown.)

  According to the method for producing a polyimide film of the present invention, since imidization is performed in a state where the polyamic acid-containing film is peeled off, the obtained polyimide film can be prevented from curling. In addition, by raising the temperature from a low temperature, a polyimide film having no whitening or foaming, good appearance and low linear expansion coefficient can be obtained.

  The method for producing a polyimide film of the present invention comprises: a) a polyamic acid containing a polyamic acid obtained by reacting a tetracarboxylic dianhydride having a specific structure with a diamine containing a diamine having a specific structure in a solvent. A step of coating the containing solution on the support; and b) the solvent in the polyamic acid-containing solution at a temperature of 150 ° C. or lower until the polyamic acid-containing film comprising the coating film of the polyamic acid-containing solution is tack-free. C) a step of peeling the polyamic acid-containing film from the support; and d) fixing the polyamic acid-containing film and heating the polyamic acid-containing film while raising the temperature from 150 ° C. or lower. And imidating the polyamic acid to obtain a polyimide film.

  As described above, when the polyamic acid is imidized, if it is rapidly heated to a high temperature, the smoothness of the surface is lowered due to the rapid volatilization of the solvent, etc., and appearance defects tend to occur. On the other hand, in the present invention, in step d) in which the polyamic acid is imidized, the temperature is raised from 150 ° C. or lower to imidize the polyamic acid. Therefore, the solvent can be volatilized gently, and the smoothness of the surface of the resulting polyimide can be improved.

  Further, when imidization is performed by rapidly heating the polyamic acid film to a high temperature, the linear expansion coefficient tends to increase. The linear expansion coefficient depends on the degree of orientation of polyimide, and the higher the degree of orientation, the lower the linear expansion coefficient. In this invention, since it heats from 150 degreeC or less and imidation of a polyamic acid is performed, the degree of orientation of a polyimide can be made high and the linear expansion coefficient of the polyimide film obtained becomes low.

  In addition, as described above, when imidizing the polyamic acid, when it is rapidly heated to high temperature, whitening due to imidization is likely to occur. Whitening due to imidization is mainly caused by crystallization of polyimide, and it is presumed that crystallization of polyimide is likely to occur when a large amount of generated water is present in the film during the imidization reaction. In the present invention, since the polyamic acid is imidized by raising the temperature from 150 ° C. or lower, the amount of produced water present in the film during the imidation reaction can be kept small, and polyimide crystals are hardly generated. Whitening hardly occurs in the polyimide film.

(1) Step a)
In step a), a polycarboxylic acid obtained by reacting a tetracarboxylic dianhydride having a specific structure with a diamine containing a diamine having a specific structure in a solvent (hereinafter also referred to as “specific polyamic acid”). The polyamic acid-containing solution containing) is applied onto the support. In the present invention, the polyamic acid may be a polyamic acid imide in which a part of the polyamic acid unit is imide-cyclized.

一般式（Ａ）中、Ｒは、炭素数４〜２７である４価の有機基であり、脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基でありうる。あるいは置換基Ｒは、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基であるか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基でありうる。 (Tetracarboxylic dianhydride)
The tetracarboxylic dianhydride constituting the specific polyamic acid is represented by the following general formula (A).

In general formula (A), R is a tetravalent organic group having 4 to 27 carbon atoms, and includes an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, and a monocyclic aromatic group. Or a condensed polycyclic aromatic group. Alternatively, the substituent R is a non-fused polycyclic aliphatic group in which the cycloaliphatic groups are directly or mutually connected by a bridging member, or the non-condensed polycyclic aliphatic group in which the aromatic groups are directly or by a bridging member. It can be a fused polycyclic aromatic group.

  The tetracarboxylic dianhydride represented by the general formula (A) may be an aromatic tetracarboxylic dianhydride or an alicyclic tetracarboxylic dianhydride.

  Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride Bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl)- 1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxy) Phenoxy) benzene dianhydride, 4,4'-bis (3,4-dicarboxyphe) Xyl) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5 , 8-Naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2 -Bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, Bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) sulfide dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, 1,3-bis (2,3-Dicarboxyphenoxy) benzene dianhydride, 1,4-bis (2,3- Carboxyphenoxy) benzene dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxybenzoyl) benzene dianhydride, 1,4-bis (3 , 4-dicarboxybenzoyl) benzene dianhydride, 1,3-bis (2,3-dicarboxybenzoyl) benzene dianhydride, 1,4-bis (2,3-dicarboxybenzoyl) benzene dianhydride, 4,4'-isophthaloyldiphthalic anhydride diazodiphenylmethane-3,3 ', 4,4'-tetracarboxylic dianhydride, diazodiphenylmethane-2,2', 3,3'-tetracarboxylic dianhydride 2,3,6,7-thioxanthone tetracarboxylic dianhydride, 2,3,6,7-anthraquinone tetracarboxylic dianhydride, 2,3,6,7-xanthone tetracarboxylic dianhydride, Ethylenetetracarboxylic acid Anhydride, and the like.

  Examples of alicyclic tetracarboxylic dianhydrides include cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic Acid dianhydride, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5, 6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, bicyclo [ 2.2.1] Heptane-2,3,5-tricarboxylic acid-6-acetic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6- Tetracarboxylic dianhydride, decahydro-1,4,5,8-dimethananaphthalene-2,3,6,7-tetracarboxylic dianhydride, 4- (2,5-dioxoteto Hydrofuran-3-yl) - tetralin-1,2-dicarboxylic acid dianhydride, 3,3 ', and the like 4,4'-dicyclohexyl tetracarboxylic dianhydride.

  When the tetracarboxylic dianhydride includes an aromatic ring such as a benzene ring, some or all of the hydrogen atoms on the aromatic ring are fluoro group, methyl group, methoxy group, trifluoromethyl group, and trifluoromethoxy group. It may be substituted with a group selected from groups and the like. Further, when the tetracarboxylic dianhydride contains an aromatic ring such as a benzene ring, the ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group depending on the purpose. , A nitrilo group, an isopropenyl group, and the like may be present as a crosslinking point. In the tetracarboxylic dianhydride, a group that becomes a crosslinking point such as vinylene group, vinylidene group, and ethynylidene group may be incorporated in the main chain skeleton, preferably within a range that does not impair molding processability. .

  In addition, a part of tetracarboxylic dianhydride may be hexacarboxylic dianhydrides or octacarboxylic dianhydrides. This is for introducing branching into the polyamide or polyimide.

  These tetracarboxylic dianhydrides can be used alone or in combination of two or more.

〔−Ｙ−は、単結合，−ＣＯ−，−Ｏ−，−ＳＯ_２−，−Ｓ−，−ＣＨ_２−，−Ｃ（ＣＨ_３）_２−，−ＣＦ_２−，−Ｃ（ＣＦ_３）_２−，−Ｏ−Ｐｈ−Ｏ−，−Ｏ−Ｐｈ−Ｃ（ＣＨ_３）_２−Ｐｈ−Ｏ−を示す〕 Furthermore, the substituent R in the general formula (A) can be represented by, for example, the following formulas (R1) to (R4).

[—Y— is a single bond, —CO—, —O—, —SO ₂ —, —S—, —CH ₂ —, —C (CH ₃ ) ₂ —, —CF ₂ —, —C (CF ₃ ) _2- , -O-Ph-O-, -O-Ph-C (CH ₃ ) ₂ -Ph-O-]

  The structure of the substituent R can be determined according to the characteristics of the polyimide film to be obtained. If the substituent R is selected appropriately, in addition to the effect that the steric stability of the polyimide film after molding can be increased, the film characteristics such as the coefficient of thermal expansion, dimensional stability, mechanical strength, flexibility and adhesiveness are arbitrary. Can be controlled.

  Thus, it is preferable to select the substituent R according to the use of the polyimide film. In addition, the substituent R may be a single type or a combination of two or more types. For example, two or more types of R may be randomly arranged in the polyamic acid.

(Diamine)
The diamine constituting the specific polyamic acid contains at least one diamine represented by the following general formulas (B-1) to (B-3). Two or more diamines represented by the following (B-1) to (B-3) may be contained in the diamine, and other than the diamines represented by (B-1) to (B-3). Diamine (B-4) may be contained.

The cyclohexane skeleton in the cyclohexadiamine represented by the general formula (B-1) can take the following two geometric isomers (cis isomer / trans isomer). The trans isomer is represented by the following general formula (B-11), and the cis isomer is represented by the following general formula (B-12).

  The cis / trans ratio of the cyclohexane skeleton in the general formula (B-1) is preferably 50/50 to 0/100, and more preferably 30/70 to 0/100. When the proportion of the trans isomer is increased, the molecular weight of the polyamic acid generally tends to increase, so that it becomes easy to form a self-supporting film, and the film made of polyamic acid is easily peeled off in step c).

  The cis / trans ratio of the unit derived from cyclohexane contained in the polyamic acid can be measured by nuclear magnetic resonance spectroscopy.

  Further, the position of the aminomethyl group of norbornanediamine represented by the general formula (B-2) is not particularly limited. For example, the norbornanediamine represented by the general formula (B-2) may include structural isomers having different aminomethyl group positions, or optical isomers including S and R isomers. These may be included in any ratio.

The 1,4-bismethylenecyclohexane skeleton represented by the following general formula (X) in the 1,4-bis (aminomethyl) cyclohexane represented by the general formula (B-3) has two geometric isomers (cis Body / trans body). The trans isomer is represented by the following general formula (X1), and the cis isomer is represented by the following general formula (X2).

  The cis / trans ratio of the unit derived from 1,4-bis (aminomethyl) cyclohexane is preferably 40/60 to 0/100, and more preferably 20/80 to 0/100. The glass transition temperature of the polyimide obtained from the specific polyamic acid containing the diamine represented by formula (B-3) as a constituent component is controlled by the cis / trans ratio of units derived from 1,4-bis (aminomethyl) cyclohexane. Can be done. That is, as the ratio of the trans form (X1) increases, the glass transition temperature of the resulting polyimide increases, that is, the heat resistance increases.

  The cis / trans ratio of the unit derived from 1,4-bis (aminomethyl) cyclohexane contained in the polyamic acid can be measured by nuclear magnetic resonance spectroscopy.

  The cis / trans ratio can be adjusted by the cis / trans ratio in 1,4-bis (aminomethyl) cyclohexane, which is a raw material monomer for polyamic acid. That is, 1,4-bis (aminomethyl) cyclohexane reacts with acid dianhydride to give polyamic acid while maintaining its geometric isomerism.

Diamines other than the diamines represented by the above general formulas (B-1) to (B-3) may be contained in the diamine. Another diamine is represented by the following general formula (B-4).

  In the general formula (B-4), R ′ is a divalent group having 4 to 51 carbon atoms; and an aliphatic group or a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group) A condensed polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a bridging member.

  Examples of the diamine represented by the general formula (B-4) include a diamine having a benzene ring, a diamine having an aromatic substituent, a diamine having a spirobiindane ring, a siloxane diamine, an ethylene glycol diamine, and an alkylene diamine. , Alicyclic diamines and the like.

Examples of diamines having a benzene ring include
<1> Diamine having one benzene ring such as p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine;
<2> 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′- Diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,4 '-Diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4- Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2,2-di (3-aminophenyl)- , 1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) ) -2- (4-Aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl) -1-phenylethane, 1,1-di ( Diamines having two benzene rings such as 4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane;
<3> 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4- Aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,4-bis ( 4-Aminobenzoyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-Amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethyl) Benzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylben) L) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 2,6- A diamine having three benzene rings such as bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine;
<4> 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- ( 4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4 -(3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophene) Noxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3- A diamine having four benzene rings such as hexafluoropropane;
<5> 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3- Aminophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, , 3-Bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4 A diamine having five benzene rings such as bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene;
<6> 4,4′-bis [4- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4 Has 6 benzene rings such as' -bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, 4,4'-bis [4- (4-aminophenoxy) phenoxy] diphenylsulfone Diamine is included.

  Examples of diamines with aromatic substituents include 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 3,3′-diamino -4-phenoxybenzophenone, 3,3′-diamino-4-biphenoxybenzophenone and the like are included.

  Examples of diamines having a spirobiindane ring include 6,6′-bis (3-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6,6′-bis ( 4-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane and the like.

  Examples of siloxane diamines include 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) ) Polydimethylsiloxane, α, ω-bis (3-aminobutyl) polydimethylsiloxane and the like.

  Examples of ethylene glycol diamines include bis (aminomethyl) ether, bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis (2-aminomethoxy) ethyl] ether, bis [2- ( 2-aminoethoxy) ethyl] ether, bis [2- (3-aminoprotoxy) ethyl] ether, 1,2-bis (aminomethoxy) ethane, 1,2-bis (2-aminoethoxy) ethane, 1, 2-bis [2- (aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3-aminopropyl) ) Ether, triethylene glycol bis (3-aminopropyl) ether, and the like.

  Examples of alkylenediamines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, and 1,8-diaminooctane. 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane and the like are included.

  Examples of alicyclic diamines include cyclobutanediamine, cyclohexanediamine, di (aminomethyl) cyclohexane [bis (aminomethyl) cyclohexane excluding 1,4-bis (aminomethyl) cyclohexane], diaminobicycloheptane, diaminomethylbicyclo Heptane (including norbornanediamines such as norbornanediamine), diaminooxybicycloheptane, diaminomethyloxybicycloheptane (including oxanorbornanediamine), isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis (aminocyclohexane) Xyl) methane [or methylenebis (cyclohexylamine)], bis (aminocyclohexyl) isopropylidene and the like.

一般式（Ｃ）及び（Ｄ）中、Ｒ及びＲ”はそれぞれ独立して、炭素数４〜２７の４価の基であり、かつ脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す。具体的には、上述の一般式（Ａ）で表されるテトラカルボン酸二無水物におけるＲと同様である。 (Preferred polyamic acid)
As the polyamic acid contained in the polyamic acid-containing solution, a polyamic acid block (in particular the following general formula) of a tetracarboxylic dianhydride represented by the general formula (A) and a diamine represented by the general formula (B-1) is used. (Represented by (C)), and a tetracarboxylic dianhydride represented by the general formula (A) and a polyimide acid block of the diamine represented by the general formula (B-4) (the following general formula (D) Are preferably combined block polyamic acid imides.

In the general formulas (C) and (D), R and R ″ are each independently a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, or a condensed polycyclic group. Whether it represents an aliphatic group, a monocyclic aromatic group, or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a bridging member, specifically, in the tetracarboxylic dianhydride represented by the above general formula (A) Same as R.

  In general formula (D), R ′ is a divalent group having 4 to 51 carbon atoms, and is an aliphatic group or a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group). A condensed polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a bridging member. Specifically, it is the same as R ′ of the diamine represented by the general formula (B-4).

  In the present invention, it is particularly preferable that R ′ in the general formula (D) is a norbornane. That is, R ′ is preferably a polyimide containing a diamine represented by the above general formula (B-2).

  M and n in Formula (C) and Formula (D) represent the number of repeating structural units in each block. The average value of m and the average value of n are each independently preferably 2 to 1000, and more preferably 5 to 500.

  The ratio of m and n is preferably an average value of m: an average value of n = 9: 1 to 1: 9, and an average value of m: an average value of n = 8: 2 to 2: 8. Is more preferable. When the ratio of the repeating number m of the repeating structural unit represented by the formula (C) is a certain value or more, the thermal expansion coefficient of the block polyimide becomes small. Moreover, the visible light transmittance | permeability of block polyimide will also become it that the ratio of the repetition number m is more than fixed. On the other hand, since cyclohexanediamine is generally expensive, reducing the ratio of the number m of repeating structural units represented by the formula (C) can reduce the cost.

  The ratio of the total number of repeating structural units represented by the formula (C) contained in the block polyimide to the total number of repeating structural units represented by the formula (D) is also (C) :( D) = 9: 1 It is preferably ˜1: 9, and more preferably (C) :( D) = 8: 2 to 2: 8.

  Moreover, in all the blocks represented by the general formula (C) contained in the block polyamic acid imide, the number of repeating structural units represented by the formula (C) is preferably 2 or more, preferably 5 or more. It is more preferable that it is 10 or more. As described above, when all of the blocks represented by the formula (C) included in the block polyimide include a certain number or more of repeating structural units, it is easy to obtain the characteristics derived from the block.

The number of repeating structural units in each block can be measured, for example, by the following method. That is, an oligomer represented by the following general formula (C ′) is reacted with a labeled sealing agent to obtain a first labeled oligomer. Similarly, an oligomer represented by the following general formula (D ′) is reacted with a labeled sealant to obtain a second labeled oligomer. And the number of repeating terminal units in each block can also be determined by quantifying the number of labeled end groups of each oligomer by the ¹ H-NMR measurement method or the like.

一般式（Ｃ’）及び（Ｄ’）におけるＲ、Ｒ’、Ｒ”、ｍ、ｎは、上述した一般式（Ｃ）及び（Ｄ）と同様である。

R, R ′, R ″, m, and n in the general formulas (C ′) and (D ′) are the same as those in the general formulas (C) and (D) described above.

一般式（Ｅ）中、Ｒは炭素数４〜２７の４価の基を示し、かつ
脂肪族基、単環式脂肪族基、縮合多環式脂肪族基、単環式芳香族基、もしくは縮合多環式芳香族基を示すか、環式脂肪族基が直接もしくは架橋員により相互に連結された非縮合多環式脂肪族基を示すか、または芳香族基が直接もしくは架橋員により相互に連結された非縮合多環式芳香族基を示す。具体的には、上記一般式（Ａ）で表されるテトラカルボン酸二無水物におけるＲと同様である。 In addition, the polyamic acid-containing solution used in step a) of the present invention preferably contains a polyamic acid containing a repeating unit of polyamic acid using a diamine represented by the formula (B-3). That is, a polyamic acid-containing solution containing a polyamic acid having a repeating unit represented by the following general formula (E) is also preferable.

In general formula (E), R represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, a monocyclic aromatic group, or A fused polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are linked directly or by a bridging member, or an aromatic group that is linked directly or by a bridging member A non-condensed polycyclic aromatic group linked to is shown. Specifically, it is the same as R in the tetracarboxylic dianhydride represented by the general formula (A).

  The polyamic acid diamine unit containing the polyamic acid repeating unit using the diamine represented by the formula (B-3) includes a diamine-derived unit other than 1,4-bis (aminomethyl) cyclohexane. Also good. For example, 1,4-bis (aminomethyl) cyclohexane and another diamine may be randomly arranged in the polyamic acid. However, 10 to 100 mol% of the total diamine units of the polyamic acid are preferably diamine units derived from 1,4-bis (aminomethyl) cyclohexane.

(Polyamic acid-containing solution)
The concentration of the polyamic acid in the polyamic acid-containing solution is preferably 1 to 50% by weight, more preferably 5 to 40% by weight. If the concentration of the polyamic acid or the polyamic acid imide exceeds the upper limit, the viscosity becomes high and it may be difficult to apply to the support. On the other hand, if it is less than the lower limit, the viscosity of the polyamic acid-containing solution is low, and it may be difficult to make the film thickness after application of the polyamic acid-containing solution uniform.

  The logarithmic viscosity at 35 ° C. of the polyamic acid-containing solution of the present invention (concentration 0.5 g / dl) when N-methyl-2-pyrrolidone is used as a solvent is 0.1 to 3.0 dl / g. Preferably there is. This is because the application of the polyamic acid-containing solution is facilitated.

  The solvent is not particularly limited as long as it can dissolve the above-described tetracarboxylic dianhydride and diamine. For example, an aprotic polar solvent or a water-soluble alcohol solvent can be used.

  Examples of aprotic polar solvents include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazo Lidinone, etc .; ether compounds such as 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether , Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-2-propanol, 1-eth Xyl-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol Diethyl ether and the like are included.

  Examples of water-soluble alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol. 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexane Triol, diacetone alcohol and the like are included.

  These solvents can be used alone or in admixture of two or more. Among these, preferred examples of the solvent include N, N-dimethylacetamide, N-methyl-2-pyrrolidone or a combination thereof.

  The polyamic acid-containing solution is obtained by reacting the above tetracarboxylic dianhydride and the above diamine in a solvent. When the number of moles of diamine in the solvent is X and the number of moles of tetracarboxylic dianhydride is Y, Y / X is preferably 0.9 to 1.1, 0.95 to 1.05 More preferably, it is 0.97 to 1.03, more preferably 0.99 to 1.01. By setting it as such a range, the molecular weight (polymerization degree) of the polyamic acid obtained can be adjusted moderately.

  There is no restriction | limiting in particular in the procedure of a polymerization reaction. For example, first, a container equipped with a stirrer and a nitrogen introduction tube is prepared. A solvent described later is put into a container purged with nitrogen, diamine is added so that the solid content concentration of the resulting polyamic acid is 50% by weight or less, and the temperature is adjusted and stirred and dissolved. This solution contains a polyamic acid containing polyamic acid by adding tetracarboxylic dianhydride so that the molar ratio is 1 with respect to the diamine compound, adjusting the temperature and stirring for about 1 to 50 hours. A solution can be obtained.

  When a block polyamic acid imide is used as the polyamic acid, for example, a polyamic acid imide may be produced by adding an acid anhydride-terminated polyimide solution to an amine-terminated polyamic acid solution and stirring. It is preferable to contain a cyclohexane-containing diamine (diamine (B-1) or (B-3)) as the diamine unit of the polyamic acid; as a polyimide diamine unit, a diamine other than the cyclohexane-containing diamine (diamine (B-2) or (B-4)) is preferably included. This is because a polyimide containing a cyclohexane-containing diamine (diamine (B-1) or (B-3)) as a diamine unit may be difficult to dissolve in a solvent. Polyamic acid may be produced as described above.

(Application of polyamic acid-containing solution)
In step a), the polyamic acid-containing liquid obtained as described above is applied on the support material. The polyamic acid coating means is not particularly limited as long as it can be applied at a desired film thickness, and for example, a known one such as a die coater, comma coater, roll coater, gravure coater, curtain coater, spray coater, lip coater or the like should be used. Can do.

  Application may be performed by a single-wafer coating apparatus or a roll-to-roll coating apparatus. In the present invention, since the polyamic acid-containing film is dried in step b) until tack-free, the laminate of the polyamic acid-containing film and the support can be wound on a roll.

  The support material on which the polyamic acid-containing liquid is applied is not particularly limited as long as the surface is smooth and the material has heat resistance and solvent resistance. Examples thereof include a glass plate, a plastic film such as polyimide or polyethylene terephthalate, and a metal plate having a mirror-finished surface. The shape of the support material is selected depending on the coating method, and may be, for example, a plate shape, a drum shape, a belt shape, a sheet shape that can be wound around a roll, or the like.

(2) Step b)
In step b), the solvent in the coating film is dried at a temperature of 150 ° C. or lower, preferably 30 to 120 ° C., until the polyamic acid-containing film comprising the coating film of the polyamic acid-containing liquid becomes tack-free. By setting the drying temperature of the solvent in step b) to 150 ° C. or less, the polyamic acid is not imidized.

  The drying of the solvent is until the resulting polyamic acid-containing film is tack-free, specifically, until the solvent concentration in the polyamic acid-containing film is 1 to 50 wt%, more preferably 10 to 35 wt%, It is preferable to dry the solvent. The amount of solvent remaining in the film can be measured by pyrolysis gas chromatography or the like.

When drying the solvent, the temperature may be constant, or the temperature may be changed in several steps. Furthermore, it may be performed while changing the temperature at a constant rate of temperature increase.
In addition, although the drying time of a polyamic acid containing film is suitably determined according to the film thickness of a polyamic acid film, the kind of solvent, a drying temperature, etc., it is normally 1 minute-60 minutes, Preferably it is 2 minutes-30 minutes. It is preferable to do. When exceeding an upper limit, it is unpreferable from the surface of the production efficiency of a polyimide film. On the other hand, when the value is lower than the lower limit, the appearance of the resulting polyimide acid film may be affected by rapid drying of the solvent.

  The method for drying the solvent is not particularly limited as long as the solvent can be dried at the above temperature. For example, an oven or a drying furnace provided in the printing machine can be used. In addition, when the sheet | seat which can be wound up by a roll is used as a support body, even if the operation | work which winds up the laminated body of a support body and the dried polyamic acid film to a roll in process b) is performed. Good.

(3) Step c)
In step c), the polyamic acid-containing film is peeled from the support. In this invention, since a support body is peeled in the state which the solvent remains in a polyamic-acid containing film, this peeling can be performed easily. Moreover, since the imidization is performed in a state where the polyamic acid-containing film is peeled off from the support in step c), the polyimidization can be performed simultaneously from both sides of the polyamic acid film, and the imidization can be performed without unevenness. It becomes. Therefore, curling of the obtained polyimide film can be prevented.

  The peeling in step c) can be performed by any method according to the shape of the polyamic acid-containing film. For example, when the polyamic acid-containing film is wound into a roll, it is possible to hold the one end of the polyamic acid-containing film and peel the polyamic acid-containing film from the support while winding the polyamic acid film. It is.

(4) Step d)
In step d), the polyamic acid-containing film is fixed, and the polyamic acid-containing film is heated while raising the temperature from 150 ° C. or less to imidize the polyamic acid to obtain a polyimide film.

The fixing method of the polyamic acid-containing film is appropriately selected according to the shape of the polyamic acid-containing film. By fixing the polyamic acid-containing film, it is possible to maintain the uniformity and flatness of the resulting polyimide film.
For example, in the case of a sheet-type polyamic acid-containing film, the periphery can be fixed to a mold or the like using clips, pins, tapes, or the like. In the case of a long polyamic acid-containing film, it can be fixed by holding one end with a tenter clip or the like.

  In step d), the temperature rise start temperature is preferably 30 ° C. or higher, more preferably 100 ° C. or higher. On the other hand, the temperature rise end temperature is preferably 200 ° C. or higher. The temperature rise end temperature is preferably 300 ° C. or lower, more preferably 280 ° C. or lower. By raising the temperature to such a range, the working efficiency becomes good and the imidization of the polyamic acid becomes possible.

  In view of the production efficiency of the polyimide film, the temperature increase rate in step d) is preferably 0.25 ° C./min or more. On the other hand, the upper limit of the heating rate is usually 50 ° C./min, preferably 40 ° C./min, and more preferably 30 ° C./min. From the point that it is possible to control the optical properties (transmittance, reflectivity, haze) by controlling the temperature increase rate, it is possible to control the appearance defect (foaming, etc.) of the film, the reduction in strength, the whitening accompanying the imidization reaction. preferable.

  The temperature rise may be continuous or stepwise (sequential), but it is preferable to be continuous from the viewpoint of controlling the appearance of the film, suppressing the strength reduction, and controlling whitening associated with the imidization reaction. Moreover, in the above-mentioned whole temperature range, the temperature rising rate may be constant or may be changed in the middle.

  In particular, in the range of 150 to 200 ° C., the average rate of temperature rise is preferably 0.25 ° C./min or more and 50 ° C./min or less, more preferably 40 ° C./min or less, further preferably 30 ° C./min. Less than minutes. In the above temperature range, it is preferable to make the temperature rising rate constant, but as long as the average speed is within the above range, it may be changed in two or more steps. When changing to two or more stages, it is preferable to set each heating rate to 0.25 ° C./min or more and 50 ° C./min or less, but as long as the average value of the heating rate is within the above range, it is temporarily It may be outside this range.

  Moreover, it is preferable to select suitably the said temperature increase rate with the film thickness of the polyimide film obtained, and when the film thickness of a polyimide film is thick, it is preferable to make a temperature increase rate slow. In the present invention, the upper limit of the film thickness of the obtained polyimide film is 500 μm or less, preferably 200 μm or less. When the film thickness of the obtained polyimide film exceeds 500 μm, it may be difficult to dry the polyimide film at the above temperature increase rate.

  In step d), the imidization ratio of the polyamic acid in the polyamic acid-containing film is preferably 30% or more, and more preferably 50% or more. By setting the imidization rate to 30% or more, after the step d), heating is performed at a high temperature for a certain period of time, and even when imidization is performed, poor appearance (foaming) or whitening of the film may occur. No increase in linear expansion coefficient or the like can occur. In step d), the reaction may be allowed to proceed to 90% or more, further 100%. The imidation ratio can be measured by analyzing the spectrum by infrared measurement (IR).

  In the step d), as a method of heating the polyamic acid-containing film while raising the temperature, when the polyamic acid-containing film is a single wafer, the polyamic acid-containing film is left in the oven and the oven temperature is raised. It can be a method of heating. In this case, the temperature increase rate can be adjusted by setting the oven.

  For example, when the polyamic acid-containing film is long, a stretching apparatus having a film transport apparatus such as a tenter can be used to pass through a heating furnace. At this time, the heating furnace has different heating temperatures along the traveling direction of the polyamic acid-containing film. In this case, the temperature increase rate can be adjusted by the conveyance speed of the polyamic acid-containing film.

  The atmosphere during heating and heating is preferably an inert gas atmosphere. When heat treatment is performed in the air, the film may be oxidized and colored, or the performance may deteriorate.

In step d), stretching may be performed simultaneously with the heating. The draw ratio is preferably -10% to 200%, more preferably -5% to 100%.
There is no restriction | limiting in particular in the extending | stretching method, For example, it can extend | stretch through a heating furnace using the extending | stretching apparatus which has conveyance apparatuses, such as a tenter.

(5) Step e)
You may perform the process of heating the polyimide film obtained at the above-mentioned process d) at 200 degreeC or more as needed. By heating the polyimide film in this step, the imidization of the polyamic acid can be further advanced. The heating temperature in this step is more preferably 200 ° C to 300 ° C. By heating in such a range, the polyamic acid can be imidized efficiently. The heating in this step is usually performed at a constant temperature.

  In this step, it is preferable that the imidation ratio of the polyamic acid is 90% or more, and more preferably the reaction is allowed to proceed to 100%.

  The step e) may be performed continuously with the step d), or may be performed after the completion of the step d), but may be performed continuously with the step d). This is preferable from the standpoint of production efficiency.

  Although there is no restriction | limiting in particular in the thickness of the polyimide film obtained by the manufacturing method of this invention, Manufacture of a 0.1 micrometer or less polyimide film may become difficult with the manufacturing method of this invention.

(6) Step f)
Moreover, in the manufacturing method of the polyimide film of this invention, the process of extending 0%-300%, fixing the said polyimide film and heating at 200 degreeC or more simultaneously after the said process e) or completion | finish of process e). Although it may be performed, it is preferable from the viewpoint of manufacturing efficiency to be performed simultaneously with the step e). The heating temperature can be the same as that in step e).

  The draw ratio of the polyimide film according to step f) is preferably 0 to 200%, more preferably 0 to 100%. By performing the above range stretching, the linear expansion coefficient of the obtained polyimide film can be made lower.

  There is no restriction | limiting in particular in the fixing method of the polyimide film at the time of extending | stretching, It selects according to the kind etc. of extending | stretching apparatus. Moreover, there is no restriction | limiting in particular in the extending | stretching method, For example, it can extend | stretch through a heating furnace using the extending | stretching apparatus which has conveyance apparatuses, such as a tenter. The polyimide film may be stretched only in one direction (longitudinal stretching or lateral stretching), or may be stretched in two directions by simultaneous biaxial stretching or sequential biaxial stretching.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited at all by these examples, and the embodiments can be changed without departing from the spirit of the present invention.

  Test methods for various tests of samples obtained in Examples and Comparative Examples are shown below.

1) Intrinsic logarithmic viscosity of polyamic acid (η)
The sample is dissolved in a diluting solvent such as N, N-dimethylacetamide (DMAc) so that the solid content concentration is 0.5 dL / g to prepare a polyamic acid-containing solution, and 35 ° C. using an Ubbelohde viscometer. The measurement was performed.

2) Amount of solvent remaining in film Measured using pyrolysis gas chromatography (Shimadzu GC-8A).

3) Glass transition temperature (Tg) and coefficient of linear expansion (CTE)
Using a TMA-50 model manufactured by Shimadzu Corporation, measurement was performed under a nitrogen stream at a heating rate of 10 ° C./min and a load per unit cross-sectional area of 14 g / mm ² . The linear expansion coefficient was measured in the range of 100 to 200 ° C.

4) Total light transmittance and haze It measured using Nippon Denshoku Industries NDH2000. During measurement, a C light source was used.

5) Reflectance Using a U-3010 spectrophotometer manufactured by Hitachi High-Technologies Corporation, the reflectance of each polyimide film at a wavelength of 300 to 800 nm was measured, and the reflectance with respect to light having a wavelength of 550 nm was defined as “reflectance”. .

6) Transparency (b *)
Measurement was performed using a color difference meter CR-300 manufactured by Minolta.
7) Tensile strength, tensile modulus, and elongation Dumbbell punched specimens were prepared and measured with a tensile tester (manufactured by Shimadzu Corp., EZ-S) under conditions of a marked line width of 5 mm and a tensile speed of 30 mm / min. It was. In the stress-strain curve obtained from five measurements, the maximum stress is “tensile strength (MPa)”, and the average stress area (integral value) until breakage is “tensile modulus (unit GPa)” In addition, the strain at that time was defined as “elongation (unit%)”.

8) Film appearance (smoothness) and shape The obtained film was visually observed and it was confirmed whether smoothness was not impaired by yuzu skin or foaming. I also checked if it was bent (curled).

  A diamine and tetracarboxylic dianhydride used as a raw material for synthesizing a polyamic acid or a block polyamic acid imide are shown.

化合物２：ノルボルナンジアミン（ＮＢＤＡ）

化合物３：３,３',４,４'-ビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）

化合物４：１,４-ビス（アミノメチル）シクロヘキサン（１，４ＢＡＣ）

Compound 1: 1,4-cyclohexanediamine (CHDA) (trans ratio 99%)

Compound 2: Norbornanediamine (NBDA)

Compound 3: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA)

Compound 4: 1,4-bis (aminomethyl) cyclohexane (1,4BAC)

Example 1
Step a)
In a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 16.0 g (0.140 mol) of 1,4-diaminocyclohexane (CHDA) and N-methylpyrrolidone (NMP) as an organic solvent ) 168 g was added and stirred. To the transparent solution, 37.1 g (0.126 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was charged in powder form, and the reaction vessel was placed at 120 ° C. And bathed in an oil bath maintained for 5 minutes. Some time after the BPDA was charged, salt precipitated, and the viscosity increased in a heterogeneous system. After removing the oil bath, the solution was further stirred at room temperature for 18 hours to obtain a solution (polyimide precursor polymer varnish) containing a polyamic acid oligomer having an amino group derived from CHDA at the terminal.

  Different from the above, in a 300 mL five-necked separable flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 12.3 g (0.0800 mol) of norbornanediamine (NBDA) and 125 g of N-methylpyrrolidone (NMP) And stirred. To the transparent solution, 29.4 g (0.100 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was charged in powder form, and the reaction vessel was placed at 120 ° C. And bathed in an oil bath maintained for 5 minutes. After the BPDA was charged, the salt temporarily precipitated, but it was confirmed that it immediately re-dissolved with a viscosity increase and became a uniform transparent solution.

  A cooling tube and a Dean-Stark type concentrator were attached to the separable flask, 80.0 g of xylene was added to the reaction solution, and the dehydration thermal imidization reaction was carried out at 180 ° C. for 4 hours with stirring. After distilling off xylene, a polyimide oligomer solution (polyimide oligomer varnish) having an acid anhydride structure derived from BPDA at the end was obtained.

  The polyamic acid oligomer solution (polyamic acid oligomer varnish) having an amino group derived from CHDA at the terminal obtained above and the polyimide oligomer solution (polyimide oligomer varnish) having an acid anhydride structure derived from BPDA at the terminal were mixed. These were stirred and defoamed to obtain a block polyamic acid imide varnish. The inherent logarithmic viscosity of the obtained block polyamic acid imide varnish was 0.74 dL / g (35 ° C., 0.5 g / dL). Further, the obtained block polyamic acid imide is obtained by polymerizing the polyamic acid oligomer and the polyimide oligomer without being randomized. The number of polyamic acid blocks: the number of polyimide blocks is approximately 2: 1 The block polyamic acid imide varnish was coated on a UPILEX film (75S) manufactured by Ube Industries, which was fixed to a glass substrate, using a single wafer coating apparatus equipped with a slot die.

Steps b) and c)
The polyamic acid imide varnish film coated on the UPILEX film as a support was transferred to an oven and heated from 30 ° C. to 120 ° C. in a nitrogen stream over 30 minutes to make tack-free. Thereby, a laminate of the polyamic acid-containing film and the UPILEX film was obtained. The polyamic acid-containing film was peeled from the UPILEX film.

Steps d) and e)
The peeled polyamic acid-containing film was fixed to the entire circumference of the stainless steel metal frame using Kapton tape. This was transferred to an oven and heated to 30 ° C. to 270 ° C. in a nitrogen stream over 2 hours. Then, it hold | maintained at 270 degreeC for further 1 hour, and obtained the 30-micrometer-thick colorless transparent polyimide film which has self-supporting property.

  The obtained polyimide film was smooth and had no curl. The amount of solvent remaining in the obtained polyimide film (N-methyl-2-pyrrolidone) was 0.2% by weight, the glass transition temperature (Tg) was 280 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 17 ppm / K. . The evaluation results of this polyimide film are shown in Table 1.

(Example 2)
Step a)
The block polyamic acid imide varnish obtained in the same manner as in Example 1 was coated on a PET film (TN-100) manufactured by Toyobo using a roll-to-roll coating apparatus equipped with a slot die.

Steps b) and c)
The polyamic acid coating film coated on the PET film was heated to 60 ° C. to 120 ° C. over 10 minutes in a drying furnace (air ventilation) attached to the above-described coating apparatus to make tack-free. Thereby, the roll film of the laminated body of a polyamic-acid containing film and PET film was obtained. The polyamic acid-containing film was peeled from the PET film while unwinding the roll-shaped laminate of the polyamic acid-containing film and the PET film.

Step d)
The end part of the peeled polyamic acid-containing film was conveyed to a drying furnace while being held by a clip tenter, and heated to 120 ° C. to 270 ° C. in a nitrogen stream over 30 minutes. Upon exiting the drying furnace, the clip tenter holding the polyimide film was removed, and a roll-shaped polyimide film was obtained using a winding device.

  The obtained polyimide film was self-supporting and was colorless and transparent with a film thickness of 30 μm. Moreover, the obtained polyimide film was smooth and had no curl. The amount of solvent remaining in the obtained polyimide film (N-methyl-2-pyrrolidone) was 0.3% by weight, the glass transition temperature (Tg) was 280 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 22 ppm / K. . The evaluation results of this polyimide film are shown in Table 1.

(Comparative Example 1)
The block polyamic acid imide varnish obtained in the same manner as in Example 1 was coated on a glass substrate using a single wafer type coating apparatus equipped with a slot die.

  The polyamic acid imide varnish film coated on the support is transferred to an oven, heated in a nitrogen stream from 30 ° C. to 270 ° C. over 2 hours, and then kept at 270 ° C. for 1 hour to dry and imidize polyimide. A film was obtained. The polyimide film produced on the glass substrate was immersed in water, and the polyimide film was peeled from the glass substrate. The adhering moisture was dried to obtain a colorless and transparent polyimide film having a film thickness of 30 μm and having self-supporting properties.

  The obtained polyimide film was smooth but curled. The amount of solvent remaining in the obtained polyimide film (N-methyl-2-pyrrolidone) was 0.3% by weight, the glass transition temperature (Tg) was 280 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 17 ppm / K. . The evaluation results of this polyimide film are shown in Table 1.

(Comparative Example 2)
The block polyamic acid imide varnish obtained in the same manner as in Example 1 was coated on a glass substrate using a single wafer type coating apparatus equipped with a slot die.

  The polyamic acid imide varnish film coated on the support was transferred to an oven, heated from 30 ° C. to 270 ° C. in a nitrogen stream over 48 minutes, and then kept at 270 ° C. for 1 hour to dry, imidize polyimide A film was obtained. The polyimide film produced on the glass substrate was immersed in water, the polyimide film was peeled off from the glass substrate, and the adhering moisture was dried to obtain a colorless and transparent polyimide film having a film thickness of 30 μm and having a self-supporting property.

  The obtained polyimide film was smooth but curled. The amount of solvent remaining in the obtained polyimide film (N-methyl-2-pyrrolidone) was 0.3% by weight, the glass transition temperature (Tg) was 280 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 22 ppm / K. . The evaluation results of this polyimide film are shown in Table 1.

(Comparative Example 3)
The block polyamic acid imide varnish obtained in the same manner as in Example 1 was coated on a glass substrate using a single wafer type coating apparatus equipped with a slot die.

  The polyamic acid imide varnish film coated on the support is transferred to an oven, heated in a nitrogen stream from 30 ° C. to 270 ° C. over 16 minutes, and then kept at 270 ° C. for 1 hour to dry and imidize polyimide. A film was obtained. The polyimide film produced on the glass substrate was immersed in water, the polyimide film was peeled off from the glass substrate, and the adhering water was dried to obtain a slightly cloudy polyimide film having a film thickness of 30 μm having self-supporting properties.

  The obtained polyimide film had yuzu skin and foaming, smoothness was impaired, and curling was also caused. The amount of solvent remaining in the polyimide film obtained (N-methyl-2-pyrrolidone) was 0.3% by weight, the glass transition temperature (Tg) was 280 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 30 ppm / K. . The evaluation results of this polyimide film are shown in Table 1.

  From the above results, the polyamic acid-containing film is peeled off from the support before imidation of the polyamic acid, and the film is heated from 150 ° C. or less to imidize to have self-supporting, smooth, curled It is clear that a film free from the above is obtained (Examples 1 and 2). Also, a continuous film can be formed by performing imidization while peeling the polyamic acid-containing film from the support (Example 2). Moreover, the polyimide film with a low coefficient of linear expansion was obtained by heating up from 150 degrees C or less and imidating (Examples 1, 2 and Comparative Examples 1-3). In Comparative Examples 1 to 3, since the polyimidation was performed without peeling the polyamic acid-containing film from the support, curling occurred in the polyimide film, and there was a problem in film quality. Moreover, in the manufacturing method of Comparative Examples 1-3, since production of a roll product is difficult, there is also a problem in productivity. On the other hand, the film obtained by the production method of the present application has no curling, is excellent in transparency and appearance, and can be suitably used for an optical film used for applications such as an image display device.

(Example 3)
Step a)
1,4-bis (aminomethyl) cyclohexane (1,4BAC) and N, N-dimethylacetamide (DMAc) as an organic solvent were added and stirred. The cis / trans ratio of 1,4-bis (aminomethyl) cyclohexane (1,4BAC) was 9/91.
Here, powdery 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) is charged, stirred, degassed, and a solution containing polyamic acid (polyimide precursor polymer) (polyimide) Precursor polymer varnish) was obtained. The intrinsic logarithmic viscosity of the obtained polyamic acid was 0.94 dL / g (35 ° C., 0.5 g / dL). The polyamic acid-containing solution was coated on a UPILEX film (75S) manufactured by Ube Industries, which was fixed to a glass substrate, using a single wafer coating apparatus equipped with a slot die.

Steps b) and c)
The polyamic acid varnish film coated on the support was transferred to an oven, heated from 30 ° C. to 100 ° C. in an air stream over 30 minutes, and tack free.
A laminate of the polyamic acid-containing film and the UPILEX film was obtained. This polyamic acid-containing film was peeled from the UPILEX film.

Steps d) and e)
The peeled polyamic acid-containing film was fixed to the entire circumference of the stainless steel metal frame using Kapton tape. This is transferred to an oven, heated to 100 ° C. to 250 ° C. in a nitrogen stream over 25 minutes, and further maintained at 250 ° C. for 1 hour to have a self-supporting colorless transparent polyimide film with a thickness of 30 μm. Got. The obtained polyimide film was smooth and had no curl. The amount of the solvent (N, N-dimethylacetamide) remaining in the obtained polyimide film was 0.1% by weight, the glass transition temperature (Tg) was 265 ° C., and the linear expansion coefficient at 100 to 200 ° C. was 51 ppm / K. . The production conditions are shown in Table 2, and the evaluation results are shown in Table 3.

(Examples 4 and 5)
A polyimide film was produced in the same manner as in Example 3 except that the film thickness in step a) and the temperature increase rate in step d) were changed as shown in Table 2. The evaluation results are shown in Table 3.

  From the results of Examples 3 to 5, it can be seen that according to the method for producing a polyimide film of the present invention, a colorless, transparent film having a self-supporting property and having no curling can be obtained. Moreover, even if it changes a temperature increase rate or the film thickness of a polyamic-acid containing film, a highly transparent polyimide film can be produced by heating from 150 degrees C or less and imidizing. The polyimide film obtained by the production method of the present invention can be suitably used for an optical film used for applications such as an image display device.

(Example 6)
Step a)
A block polyamic acid imide varnish was obtained in the same manner as in Example 1 except that the weight ratio of CHDA to NBDA was changed to 3.15 / 1. The inherent logarithmic viscosity of the obtained block polyamic acid imide varnish was 0.84 dL / g (35 ° C., 0.5 g / dL). The obtained block polyamic acid imide varnish was coated on a PET film (TN-100) manufactured by Toyobo using a single wafer type coating apparatus equipped with a slot die.

Steps b) and c)
The polyamic acid imide varnish film coated on the support was transferred to an oven, heated from 30 ° C. to 100 ° C. in an air stream over 30 minutes, and tack free. Thereby, the laminated body of the polyamic-acid containing film and PET film was obtained. The polyamic acid-containing film was peeled off from the PET film from the laminate.

Steps d) to f)
The peeled polyamic acid-containing film was fixed to the entire circumference of the stainless steel metal frame using Kapton tape. This was transferred to an oven and heated to 30 ° C. to 270 ° C. in a nitrogen stream over 1 hour. Subsequently, it was kept at 270 ° C. for 1 hour to obtain a colorless and transparent polyimide film having a film thickness of 30 μm and having a self-supporting property.

  Both ends of the obtained polyimide film were sandwiched between stretching devices having clip tenters, set in a heating furnace, the temperature of the heating furnace was raised to 300 ° C., and then the uniaxial direction of the film was stretched by 25%.

  The obtained polyimide film was smooth and had no curl. The total amount of solvent (N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone) remaining in the obtained polyimide film is 0.01% by weight or less, and the glass transition temperature (Tg) is The linear expansion coefficient at 271 ° C. and 100 to 200 ° C. was −3 ppm / K (stretching direction). The production conditions are shown in Table 4, and the evaluation results of the obtained polyimide film are shown in Table 5.

(Example 7)
A polyimide film was produced in the same manner as in Example 6 except that the draw ratio of the polyimide film was changed as shown in Table 4. Table 5 shows the evaluation results of the obtained polyimide film.

(Example 8)
Steps a to c)
In the same manner as in Example 6, a polyamic acid-containing solution and a laminate of the polyamic acid-containing film and the PET film were obtained. The polyamic acid-containing film was peeled from the PET film.

Steps d) and e)
Four corners were fixed using a Kapton tape on a stainless steel metal frame so as not to apply tension to the peeled polyamic acid-containing film. This is transferred to an oven, heated in a nitrogen stream to 30 ° C. to 270 ° C. over 1 hour, and then further maintained at 270 ° C. for 1 hour to have a self-supporting film thickness of 30 μm of colorless and transparent polyimide film Got. The dimension of the obtained polyimide film shrunk by 5%. The production conditions are shown in Table 4, and the evaluation results of the obtained polyimide film are shown in Table 5.

Example 9
A polyimide film was obtained in the same manner as in Example 6 except that stretching was not performed. The production conditions are shown in Table 4, and the evaluation results of the obtained polyimide film are shown in Table 5.

From the results of Examples 6 to 9, it can be seen that according to the method for producing a polyimide film of the present invention, a smooth, colorless and transparent film having self-supporting properties can be obtained. Moreover, it is possible to produce a polyimide film having a low linear expansion coefficient and high transparency by raising the temperature from 150 ° C. or less and imidizing. In addition, it is also clear that the linear expansion coefficient decreases by performing the stretching (Examples 6 and 7). Moreover, even if the same unstretched, the linear expansion coefficient is smaller when fixing to the metal frame in step d) is fixed all around (Example 9) than when not fixed all around (Example 8). Lower.
In addition, since the polyimide film obtained by the production method of the present invention has a good appearance, no curling, and a low coefficient of linear expansion, it is suitably used for an optical film used for an image display device or the like. I can do things.

(Examples 10 and 11)
Steps a to e)
1,4-bis (aminomethyl) cyclohexane (1,4BAC) and N, N-dimethylacetamide (DMAc) as an organic solvent were added and stirred. The cis / trans ratio of 1,4-bis (aminomethyl) cyclohexane was 14/86.
Here, powdery 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) is charged, stirred, degassed, and a solution containing polyamic acid (polyimide precursor polymer) (polyimide) Precursor polymer varnish) was obtained. The intrinsic logarithmic viscosity of the obtained polyamic acid was 1.22 dL / g (35 ° C., 0.5 g / dL).
By using the obtained polyamic acid-containing solution, a polyimide film before stretching was obtained in the same manner as in Example 6.

Step f)
A polyimide film was produced in the same manner as in Example 6 except that the stretching method, stretching ratio, and temperature of the polyimide film were changed as shown in Table 6. Table 7 shows the evaluation results of the obtained polyimide film. In addition, since Example 10 extended | stretched to the biaxial direction, the linear expansion coefficient was measured about each extending direction.

  From the results of Examples 10 and 11, it can be seen that according to the method for producing a polyimide film of the present invention, a smooth, colorless and transparent film having self-supporting properties can be obtained. It can also be seen that the higher the draw ratio, the lower the linear expansion coefficient (Example 10). Moreover, it is possible to produce a polyimide film having a low linear expansion coefficient and high transparency by raising the temperature from 150 ° C. or less and imidizing. In addition, in any of the uniaxial and biaxially stretched films, the appearance was excellent and there was no curl. Such a polyimide film obtained by the production method of the present invention can be suitably used for an optical film used for applications such as an image display device.

  The polyimide film produced by the method for producing a polyimide film of the present invention has no curling, a small thermal expansion coefficient, and no whitening. Therefore, it is preferably used for optical films such as image devices, polyimide metal laminates for circuit boards, and the like.

Claims (8)

a) At least one selected from the group consisting of tetracarboxylic dianhydrides represented by the following general formula (A) and diamines represented by the following general formulas (B-1) to (B-3) is included. A step of applying a polyamic acid-containing solution containing a polyamic acid obtained by reacting a diamine in a solvent onto a support;
b) drying the solvent in the polyamic acid-containing solution at a temperature of 150 ° C. or lower until the polyamic acid-containing film comprising the coating film of the polyamic acid-containing solution is tack-free;
c) peeling the polyamic acid-containing film from the support;
d) fixing the polyamic acid-containing film, heating the polyamic acid-containing film while raising the temperature from 150 ° C. or less, and imidating the polyamic acid to obtain a polyimide film, thereby producing a polyimide film .

(In the general formula (A), R represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, a monocyclic aromatic group, Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group directly or by a bridging member (Shows non-condensed polycyclic aromatic groups linked together)

The method for producing a polyimide film according to claim 1, further comprising: e) a step of heating the polyimide film at 200 ° C. or higher after the step d). At the same time as step e) or after step e),
The manufacturing method of the polyimide film of Claim 2 including the process of fixing the circumference | surroundings of the said polyimide film, heating the said polyimide film 0%-300%, heating at 200 degreeC or more.   The method for producing a polyimide film according to any one of claims 1 to 3, wherein the step d) is a step of heating the polyamic acid-containing film while raising the temperature from 150 ° C or lower to 200 ° C or higher.   The manufacturing method of the polyimide film of Claim 4 whose average temperature increase rate in the temperature range of 150 degreeC-200 degreeC of the said process d) is 0.25-50 degreeC / min.   The method for producing a polyimide film according to any one of claims 1 to 5, wherein the step b) is a step of setting the solvent concentration remaining in the polyamic acid-containing film to 1 to 50% by weight. The polyamic acid-containing solution includes a polyamic acid block composed of a repeating structural unit represented by the following general formula (C) and a polyimide block composed of a repeating structural unit represented by the following general formula (D). The manufacturing method of the polyimide film as described in any one of Claims 1-6 containing the block polyamic-acid imide to contain.

(In the general formulas (C) and (D), R and R ″ are each independently a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, or a condensed polycycle. Represents a non-condensed polycyclic aliphatic group in which a cyclic aliphatic group, a monocyclic aromatic group, or a condensed polycyclic aromatic group, or a cyclic aliphatic group connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member;
In the general formula (D), R ′ is a divalent group having 4 to 51 carbon atoms, and an aliphatic group, a monocyclic aliphatic group (excluding a 1,4-cyclohexylene group), a condensed group. A polycyclic aliphatic group, a monocyclic aromatic group or a condensed polycyclic aromatic group, or a non-condensed polycyclic aliphatic group in which the cyclic aliphatic groups are connected to each other directly or by a bridging member Or a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridging member) The polyamic acid has a repeating unit represented by the following general formula (E),
The 1,4-bismethylenecyclohexane skeleton (X) in the general formula (E) is composed of a trans isomer represented by the formula (X1) and a cis isomer represented by the formula (X2).
The content ratio of the trans isomer to the cis isomer (trans isomer + cis isomer = 100%) is 60% ≦ trans isomer ≦ 100%, 0% ≦ cis isomer ≦ 40%. The manufacturing method of the polyimide film as described in a term.

(In General Formula (E), R represents a tetravalent group having 4 to 27 carbon atoms, and an aliphatic group, a monocyclic aliphatic group, a condensed polycyclic aliphatic group, a monocyclic aromatic group, Or a condensed polycyclic aromatic group, a non-condensed polycyclic aliphatic group in which the cycloaliphatic groups are linked directly or by a bridging member, or an aromatic group directly or by a bridging member (Shows non-condensed polycyclic aromatic groups linked together)